Surveillance of foreign leaders provides world powers — Britain then, America now — with critical information for the exercise of global hegemony. Such spying gave special penetrating power to the imperial gaze, to that sense of superiority necessary for dominion over others. It also provided operational information on dissidents who might need to be countered with covert action or military force; political and economic intelligence so useful for getting the jump on allies in negotiations of all sorts; and, perhaps most important of all, scurrilous information about the derelictions of leaders useful in coercing their compliance.